(a) Field of the Invention
The present invention is related to an improved structure of a backlight module light distributing device, and more particularly to one that effectively light from light sources without developing bright bands and dark bands.
(b) Description of the Prior Art
As illustrated in FIG. 1 (A) of the accompanying drawings for an improved structure of a LCD backlight module of the prior art, the backlight module is essentially comprised of a reflector mask 10, multiple light sources 20, a diffuser plate 30, a lower diffuser sheet 40, a prism 50, a reflective polarizing sheet or an upper diffuser sheet 60 and a LCD 70 arranged in sequence from inside out. Wherein, those light sources 20 may be each a light tube in a stripe, U-shape or other continuous curve. The light sources 20 may be arranged at a proper spacing between the reflector mask 10 and the diffuser plate 30 and the light emitted by each of the light sources 20 provides the display effects on the LCD module. As generally found available in the market, multiple optical films disposed between the diffuser 30 and the LCD module may be comprised of 1-3 diffuser sheets, 0-2 brightness enhancement films and one reflective polarizing sheet for the purpose of diffusing the light passing through those optical films so as to correct the phenomena of bright bands and dark bands forming on the LCD module due to the absence of light emitted from the space between adjacent light sources.
Whereas the diffuser plate 30 functions only to help achieve the even diffusion for lights passing through it, it has a limited efficiency in correcting the phenomenon of the bright bands and the dark bands observed on the LCD module. To address this, an improvement is made for certain backlight modules by extending the distance between those light sources 20 and the diffuser plate 30 in order to increase the areas of the diffuser plate 30 illuminated by the light source 20 to effectuate greater dispersion of the light entering the diffuser plate 30 to thereby achieve the purpose of reducing the dark bands. However, the structural design for such an improvement not only provides limited effects but also causes the backlight module to be thicker thereby making the LCD module too large.
Furthermore, some other backlight modules seek to provide extinction (dispersion) on the surface of the diffuser plate by printing on the diffuser plate with ink containing SiO2 or TiO2 to achieve the purpose of reducing the dark band. Again, this extinction process not only increases the production cost of the diffuser and the complexity of the manufacturing process, but also only provides a passive solution to reduce the dark bands on the LCD since the extinction is created only after the light lands on the surface of the diffuser.
Further improvement as illustrated in FIG. 1(B), multiple light distributing devices 12 are provided on the reflector mask 10 of the backlight module. The highly reflective surface of the light distributing device 12 reflects the light emitted from the light source 20 to eliminate the dark band between any abutted light sources 20. However, the light distributing 12 integrated with the reflector mask 10 functions only for the purpose of reflective distribution and fails to provide a refractive or diffusive distribution function.